BZOJ 2442 修剪草坪

NOIP的时候一定要看清楚数据范围。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define maxn 100500
using namespace std;
long long n,k,sum[maxn],dp[maxn],a[maxn],c[maxn],q[maxn],l=1,r=0,ans=0;
int main()
{
    scanf("%lld%lld",&n,&k);
    for (long long i=1;i<=n;i++)
    {
        scanf("%lld",&a[i]);
        sum[i]=sum[i-1]+a[i];
    }
    c[1]=-sum[1];
    for (long long i=1;i<=k;i++)
    {
        dp[i]=sum[i];ans=max(ans,dp[i]);
        c[i+1]=dp[i]-sum[i+1];
        while ((l<=r) && (c[q[r]]<=c[i])) r--;
        q[++r]=i;
    }
    for (long long i=k+1;i<=n;i++)
    {
        while ((l<=r) && (q[l]<i-k)) l++;
        dp[i]=c[q[l]]+sum[i];ans=max(ans,dp[i]);
        c[i+1]=dp[i]-sum[i+1];
        while ((l<=r) && (c[q[r]]<=c[i])) r--;
        q[++r]=i;
    }
    printf("%lld\n",ans);
    return 0;
}